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Active Tectonics of Northeast Asia: Using Block Modeling to Test Okhotsk Plate Motion Independent From North Americaтезисы доклада
- Авторы: Apel E.V., Burgmann R., Kogan M., King R., Vasilenko N.F., Levin V.I., Steblov G.M., Frolov D.I., Ivaschenko A.I., Gordeyev Y.I.
- Сборник: American Geophysical Union (AGU) 2004 Western Pacific Geophysics Meeting
- Серия: Eos, Transactions American Geophysical Union
- Том: 85
- Тезисы
- Год издания: 2004
- Первая страница: T34A-06
- Аннотация: Horizontal surface velocities of 81 GPS sites (39 from the Eurasian, North American and Pacific plate and 42 from NE Asia) constrain the plate kinematics of NE Asia and allow for a rigorous test of the possibility of Okhotsk plate motion independent of the North American plate. A block modeling approach is used to incorporate both rigid block rotation and near-boundary elastic strain accumulation effects in a formal inversion of the GPS velocities. Considered models include scenarios with and without independent Okhotsk plate motion and a number of different plate boundary locations and locking depths. Our modeling favors a scenario with independent Okhotsk plate motion but does not require it, based on the application of F-test statistics. Euler poles, calculated from our optimized inversion, suggest an independent Okhotsk plate rotating 0.02-0.03 deg/Myr faster about a pole northeast of the North American pole of rotation with respect to Eurasia. The plate-motion parameters of the Okhotsk plate are consistent with right-lateral motion in northern Sakhalin and contraction in southern Sakhalin, inferred from focal mechanism solutions. However, subtle changes in block and segment geometry can cause significant changes in the estimated pole of rotation of the Okhotsk plate. This is due, in large part, to the close proximity of most GPS stations in northeast Asia to plate boundaries, such as the Kamchatka-Kurile subduction zone and Sakhalin Island contraction and strike-slip shear zone. GPS velocities on the Kamchatka peninsula capture a complex pattern associated with the locked subduction zone. This locked subduction zone may require a more complex model than a simple elastic dislocation for the rotational signal to be resolvable. We will also consider the possible influence of an independent Amurian plate that may also affect the determination of Okhotsk plate existence and motion.
- Добавил в систему: Стеблов Григорий Михайлович